Automated washing machines (such as laundry washing machines) often include mechanisms for dispensing additives into a washing chamber (e.g., a rotating drum). Such mechanisms may include dispenser drawers that have chambers or compartments for holding and dispensing different additives, which additives may include detergents, whiteners, fabric softeners, scents, rinse aids, etc. Typically, a user fills one or more dispenser chambers with additives. At selected times during a wash cycle, water is then automatically introduced into the dispenser chamber(s) and mixes with the additive(s). The water/additive mixture then flows out of the dispenser drawer and into the drum or other washing chamber.
An example of a drawer-style additive dispenser is illustrated and described in commonly-owned U.S. Patent Application Publication No. 2004/0011089 (titled “Washing Aid Dispenser and Washing Machine Comprising Said Dispenser”). Access to the drawer by the user is obtained by withdrawing the drawer from an associated dispenser housing provided within the appliance cabinet. Typically, the drawer slides in and out of the dispenser housing along guideways provided on opposite sides of drawer, and on corresponding sides of the cavity that receives the drawer. Examples of drawer-style additive dispensers with frictional slide guides can be seen in U.S. Patent Application Publication No. 2006/0162392, U.S. Patent Application Publication No. 2007/0079637, U.S. Pat. No. 7,093,467, and U.K. Patent No. 1,211,560.
In a modern trend, laundry appliances are taking on a more prominent stylistic role in the home. As part of this trend, greater emphasis is often placed on convenience, user friendliness, and the “look and feel” of laundry appliances. An additive dispenser drawer that operates more smoothly and easily, and which presents a solid feel to a consumer, can provide significant utility. For example, persons shopping for a new washing machine will typically operate readily accessible mechanical features such as a dispenser drawer when examining various makes and models on a retail showroom floor. Consumers will likely consider a smoothly-operating dispenser drawer having a solid feel as indicative of a well designed and well built appliance. Conversely, a consumer may feel that a dispenser drawer operating less smoothly or having excessive side-to-side or vertical looseness (“play”) in the drawer mechanism is indicative of poor design or poor workmanship.
One way to improve smoothness of drawer operation and to provide a more solid-feeling mechanism is to include a more sophisticated linear bearing system. Previous efforts to include such bearing systems can be seen in European Patent Application Publication No. 1449952 and in German Patent Application Publication No. 10061155. These and similar efforts have provided incomplete or impractical solutions, however. As with many consumer appliances, minimizing manufacturing costs can be a critical consideration in any design. Many of the known prior art drawer designs utilize a linear bearing system that would be expensive to manufacture, would require enlarging the size of a dispenser drawer, or would otherwise have undesirable consequences.